Turing’s work more prescient than ever

Alan Turing didn’t live to see his 100th birthday. Yet thanks to his pioneering work in computer science, cryptanalysis and artificial intelligence, his immortality is assured. And as Andrew Hodges explains in his seminal biography Alan Turing: The Enigma, Turing led a life that was the stuff of dreams. And nightmares.

Turing was born 100 years ago today, on June 23, 1912, to an upper middle class couple in London, England. His scientific and mathematical prowess was evident from an early age, and it led him to King’s College, Cambridge, where he graduated with a degree in math in 1934.

He became a fellow the following year, and it took only one more year for Turing to write his name in history. For it was in 1936 that he published his first masterpiece, On Computable Numbers, with an Application to the Entscheidungsproblem.

That’s an imposing title, referring as it does to the “decidability problem,” one of the philosophical problems of pure mathematics outlined by German mathematician David Hilbert. And the paper itself was equally imposing, as it was heavily influenced by Austrian-American logician Kurt Godel’s famous incompleteness theorem, and therefore probed deeply into mathematical logic.

Yet the paper also introduced two key concepts that would ensure Turing’s immortality: The Turing machine, a set of instructions for calculating — or what we would today call an algorithm, or even more familiarly, a computer program; and the Universal Turing machine, which interprets and follows such instructions — or what we would today call a computer.

So by 1936, Turing had already outlined, in some detail, both the modern computer and modern computer software. They were only in his head, of course, but Turing had no intention of keeping them there; rather, he had every intention of making the then-non-existent computer a reality.

And those aspirations were aided by Turing’s code-breaking work with the British Government Code and Cypher School, which was headquartered in an ugly mansion with an ugly name — Bletchley Park. Having begun part-time work in 1938, he started full-time employment at Bletchley Park in 1939, one day after the United Kingdom declared war on Germany.

Among other things, Turing and his colleagues worked on deciphering secret messages encrypted by the German machine known as Enigma. Turing himself focused on the German U-boat messages, which were largely regarded as unbreakable — at least until Turing put his mind to breaking them.

But unlike Turing’s earlier work, not everything at Bletchley Park was in his mind. Rather, Turing and fellow mathematician Gordon Welchman developed the Turing-Welchman Bombe, an electromechanical device that aided in breaking the Enigma messages. The Bombé was not a full-fledged computer, but it did involve the marriage of mathematics and electronic technology and was therefore an important step on the road to the computer.

That road appeared near an end after the war, as Turing was appointed senior principal scientific officer at the British National Physical Laboratory, with responsibility for “building a brain” — that is, developing a computer. Turing’s proposal for an Automatic Computing Engine (ACE) was accepted in 1946, and he began work on programming languages shortly after. Yet for a variety of reasons, the ACE was never built.

Turing therefore returned to Cambridge in 1947, and then moved on to the University of Manchester in 1948. And it was while in Manchester that Turing wrote his second masterpiece, Computing Machinery and Intelligence, which laid the foundations for the philosophy of artificial intelligence.

The paper also introduced the Turing Test, which Turing suggested could answer the question “Can machines think?” Although several variations of the test exist, Turing first proposed a variation of an old parlour game called the imitation game.

The game is played with three people: a man, a woman and an interrogator.

The interrogator stays in a room separate from the other two, and must determine, through a series of typewritten questions and answers, which is the man and which the woman.

Turing then proposed that a computer take the place of the man, and he concluded that the computer is effectively thinking if the interrogator is unable to tell the difference between the computer and the man.

The test is still conducted today, albeit in slightly different form, although there is intense debate about whether it is an appropriate method of determining if machines can think. But there is no debate about the importance of Computing Machinery and Intelligence, which remains one of the most frequently cited philosophical papers more than 60 years after it was published.

Likewise, there is no debate about the importance of Turing’s groundbreaking work. For his early work he was elected a fellow of the Royal Society, and in 1945, he received the Order of the British Empire for his work during the Second World War, work that, according to some estimates, saved millions of lives.

Yet much of that work remained secret during Turing’s life; in fact, two papers he wrote while at Bletchley Park were only released in April of this year.

Not so for his personal life, and in particular his romantic life, as Turing was never secretive about his homosexuality. This proved to be of little hindrance in the liberal confines of King’s College, but it was a different story in Manchester.

Indeed, after reporting a break-in at his house, Turing freely admitted that he had previously been sexually involved with the burglar ­— an admission that led to Turing being charged with gross indecency under section 11 of the Criminal law Amendment Act 1885, the same law that led to Oscar Wilde’s imprisonment.

Yet it proved to be something of a death sentence, for just two years later Turing was found dead at age 41, the victim of an apparent suicide by cyanide poisoning.

Amazingly, the law that played a role in Turing’s death was not repealed until 1967.

More amazing still, the British government did not apologize for its treatment of Turing until 2009, when then-prime minister Gordon Brown said Turing was “tried for being gay” and concluded “I’m very proud to say: we’re sorry. You deserved so much better.”

It’s easy to wonder if Turing could have predicted such progress, where persecution has given way to praise. But then, much of that progress is directly attributable to Turing himself.

For like all good visionaries, Turing didn’t merely predict the future; he created it.

pmcknight@vancouversun.com

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Turing’s work more prescient than ever

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